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[danhardison]

Hello,
I have an iFi Micro iDSD dac that is supposed to be able to play all high def formats known to man. (http://ifi-audio.com/portfolio-view/micro-idsd/)
I have downloaded some sample high def tracks and I am getting the attached down-sampling notification in the Audio Path window.
I don't know if this is a limitation of my pc, Media Center or the DAC. Or if there is some configuration I should change.
I have attached screenshots of the file details, and the resultant audio path output.
Has anyone been down this path? Any advice appreciated.
Dan

[blgentry]

By default, MC converts DSD to PCM and then uses the DSP Studio settings to decide exactly what rates of PCM get sent to the DAC itself.

Try one change at a time.

First, set up bitstreaming for DSD.  This will make MC send the actual DSD bitstream to your DAC instead of converting it to PCM.  Note that you lose the ability to control any processing on DSD tracks when you do this. No volume, no EQ, ... nothing in DSP Studio will work in DSD because MC is going to send it directly to your DAC.

Tools > Options > Audio > Settings > Bitstreaming > DSD

After you get that working successfully, you should examine the Output Format settings.  Player > DSP Studio > Output Format

Look at the matrix in the lower left/center.  It maps input rates to output rates.  Configure this to send what your DAC can handle.

Good luck.

Brian.

[danhardison]

Thanks.

I did this, and I am still getting the same results on that 11.2Mhz track. Interestingly, it doesn't matter if I set the sample rate option in DSP Studio to "Set all to no change", next time I look it has reverted back to setting everything above 192,000Hz to 176,400. Is this because it has detected that as a limitation in my DAC?

And more interestingly, when I play another track that is 2.8Mhz, it plays it with no changes, even though that is above 192,000..

See attached.

[blgentry]

That 11.2 MHz file is quad rate DSD.  I *thought* that would just bitstream normally.  But I don't have any experience with DSD DACs, so I'm not sure.  My DAC only supports PCM, so I convert from DSD to PCM and go from there.

Obviously single rate DSD is working with bitstreaming (2.8 MHz).  I'm not sure where the problem lies.  I don't use MC on Linux, so I'm not super familiar with audio setup with MC for Linux.

Maybe Bob or Mwilliems or one of the other Linux "heavies" will weigh in.

Brian.

[danhardison]

No worries. Thanks for replying. I will keep reading.
Dan

[mwillems]

First questions: what linux distro/kernel version are you running?  DSD support is fairly "new" in the Linux kernel, so, for example, Debian stable's kernel doesn't have DSD support yet. Additionally, my understanding was that DSD512 may have been the maximum supported, but my research on this is about 6 months old so higher rates may have been implemented since then.

Additionally, my recollection is that MC's support for quad DSD (11.2 MHZ) is also fairly new, and may not have migrated into the Linux version.  Maybe Bob can weigh in on the status of quad DSD support for Linux?

I don't have any DSD capable devices, so can't provide solid reproducible guidance unfortunately, other than: make sure your kernel is modern enough to support it.

Some (admittedly dated) info in this thread: http://www.head-fi.org/t/728236/ifi-idsd-micro-dsd512-pcm768-dac-and-headphone-amp-impressions-reviews-and-comments/1620

[danhardison]

Hi,
I'm running debian jessie. 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt11-1+deb8u6 (2015-11-09) x86_64 GNU/Linux

The DSD support seems to be there, because I can play the example attached at 2.8Mhz and it says "no changes are being made", if I understand that correctly.

I don't understand the Sample Rate settings in DSP Studio. I set them all to No Change, and they stay like that for everything up to the 2.8Mhz DSD tracks, but when I play the 11.2Mhz track, it changes by itself to the attached (setting everything above 192,000 to 176,400.)

I am just curious about all this. I am trying things out in high def to see how good this DAC is. It's not mission critical! But I'd like to hear peoples experiences and/or opinions on the matter.

Dan

[mwillems]

Hi,
I'm running debian jessie. 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt11-1+deb8u6 (2015-11-09) x86_64 GNU/Linux

The DSD support seems to be there, because I can play the example attached at 2.8Mhz and it says "no changes are being made", if I understand that correctly.

I don't understand the Sample Rate settings in DSP Studio. I set them all to No Change, and they stay like that for everything up to the 2.8Mhz DSD tracks, but when I play the 11.2Mhz track, it changes by itself to the attached (setting everything above 192,000 to 176,400.)

I am just curious about all this. I am trying things out in high def to see how good this DAC is. It's not mission critical! But I'd like to hear peoples experiences and/or opinions on the matter.

Dan

High rate DSD and DOP were added in kernel 3.19, so after Jessie.  If I had to guess I'd say that's your issue.

[danhardison]

Oh OK!

So do you think if I upgrade the kernel, MC will work?

Thanks

[mwillems]

I can't be sure because I don't own any DSD hardware, but have a look at the thread I linked above.

It looks like proper DSD support was added in 3.18 and 3.19.  You'd need a kernel above 3.18 and a certain ALSA version as well. 

[phillil]

I'm not sure about DSD on my system, but I have many HD FLAC files and they play with no problems (96/192kHz) on my USB DAC

[bob]

...
I don't understand the Sample Rate settings in DSP Studio. I set them all to No Change, and they stay like that for everything up to the 2.8Mhz DSD tracks, but when I play the 11.2Mhz track, it changes by itself to the attached (setting everything above 192,000 to 176,400.)
...

MC will autoswitch the sample rate on playback failure.
To disable this, see Options->Audio->Advanced.

[phillil]

I'm not sure about DSD on my system, but I have many HD FLAC files and they play with no problems (96/192kHz) on my USB DAC

Actually I stand corrected...

My DAC supports upto 96kHz, so when a track that is 192kHz plays, JR auto converts to 96kHz and as a result it just produces a load of pink noise.

When using the PC, the conversion down to 96kHz works fine

[danhardison]

Thanks for all your replies.

In summary, I haven't found anything that I can't play.. and it all sounds good.

I am just playing around to see what is possible. I will look into updating the kernel to get greater DSD support... but I am a bit scared of this  ;-)

I highly recommend the ifi micro iDSD DAC.

[blgentry]

My DAC supports upto 96kHz, so when a track that is 192kHz plays, JR auto converts to 96kHz and as a result it just produces a load of pink noise.

That shouldn't happen.  Are you sure DSP Studio is set to convert 192 to 96?  Do plain 96kHz files play ok?  Have you tried this with more than one 192kHz file?  Maybe it's a bug.  It just seems unlikely.

Brian.

[danhardison]

An update..

I upgraded my kernel to 4.3, which was quite painless, but it made no difference to what I was seeing before.

I think there might be some ALSA configuration required, but I haven't figured out exactly what needs to be done.

[phillil]

That shouldn't happen.  Are you sure DSP Studio is set to convert 192 to 96?  Do plain 96kHz files play ok?  Have you tried this with more than one 192kHz file?  Maybe it's a bug.  It just seems unlikely.

Brian.

Hi Brian, yes 96kHz play fine. I will test some other 192kHz files later, but i've never noticed it before with JR on my PC
Thanks